10 mm matching spring to load

Having never shot the caliber, I wanted to rent a 10mm pistol, and the most convenient option was an EAA Witness, standard metal frame. I was a little apprehensive, having got the characteristic "trigger sting" from the Cz 75 9mm I tried last summer. It was a blast! (no pun intended) No problem with the trigger. Maybe the EAA's is wider.

Recoil was less than I'd expected. The shop said their 180 gr. ammo was "about 1200 fps." I'd forgotten what brand, but then I found a couple of casings in my range bag and it's PPU headstamped. Intertubez say that is only 990 FPS with 180 gr. bullets! Definitely 10 mm Lite. I knew I wasn't so tough! I was at the range last weekend and started trading guns with the guys in the next lane. One of them gave me ten rounds through his .40SW Glock, which didn't feel much different than I remember from the EAA.

The rental 10 mm functioned perfectly on this stuff, at least through one box. I'll assume that's with a stock recoil spring. (I'd call the range and ask but since they were about 40% off on the muzzle energy of the ammo, I wouldn't trust their answer anyway.) Plinking with something like this would be fine, but the fun of a 10 mm would be to go full-house as least some of the time. If I buy a 10 mm, I plan to load my own ammo.

How wide a range of velocity/energy variation can you get before it's necessary to go to a higher spring rate to avoid slamming the slide?

Are appropriate spring rates determined simply by muzzle energy, or is light and fast different than heavy and slow at the same foot-pounds?

I have a witness Match 10mm and shoot loads at various power levels. You can find many people who say that they come underspung for 10mm at about 12 lb. When I got mine, my initial approach was to run the heaviest spring that doesn't generate FTF/FTE problems. I haven't used something hot enough yet to get a 20lb spring to work 100%, but some things run 18lb'ers well. Going to 16lb seems to run everything.

There is dispute here on THR as to whether the spring does anything meaningful to reduce frame/slide battery. Some say anything that will return the gun to battery is strong enough.

hentown

December 4, 2012, 05:00 PM

I never shot a 10mm other than my Glock 20 and 29. I use recoil springs that are about 5# heavier than the stock springs. If your pistol is ejecting brass father than about 8', then you need a stronger spring.

Buck13

December 4, 2012, 06:08 PM

There is dispute here on THR as to whether the spring does anything meaningful to reduce frame/slide battery. Some say anything that will return the gun to battery is strong enough.

Yep. There's even a strain of argument that the mass of the slide is far and away the most important contributor (other than force from the cartridge) in determing slide velocity, with any fooling around with springs being just that - fooling.

In any event, Wolf recoil springs for Tanfoglios are cheap, so I've gotten a number of them and, as described above, worked from heaviest down until I found the heaviest spring that would feed reliably. If the spring gets too strong, the slide either short-strokes or returns faster than the magazine spring can accelerate the next round up into position for feeding. When I use a spring that's too strong, I tend to get FTFs where the round gets caught about halfway. Anyway, as I said, 16lb seems to be a good weight for most of what I shoot, from the PriviPartizan (PPU brass) stuff you encountered to rounds actually developing 1200+ with 180 grains.

hentown

December 5, 2012, 09:01 AM

I'd have to think that those making that "strain of an argument" regarding slide mass never took h.s. physics and probably don't know much about firearms. :cool:

1911Tuner

December 5, 2012, 09:29 AM

Yep. There's even a strain of argument that the mass of the slide is far and away the most important contributor (other than force from the cartridge) in determing slide velocity, with any fooling around with springs being just that - fooling.

Not exactly. While mass and momentum carry the most potential for damage in any impact event...momentum is a function of mass times velocity...so the velocity of the moving object is always a factor.

But...

The slide just doesn't hit the frame all that hard, even without a spring. I once proved that to a skeptic by firing a Colt LW Commander over a hundred times without a spring. No damage was noted. For this demonstration, I suggest using a full-length guide rod and matching plug because the standard 'stub" rod will cant upward and cause damage.

Consider the 5-inch .45 caliber 1911. The slide and barrel's mass is some 33 times greater than the bullet. Assuming 230-grains at 830 fps, rough calculations place the slide's maximum velocity at around 22 fps. The slide is only being accelerated during the time that the bullet is in the barrel...nominally 1/10th inch of rearward slide travel. Once the bullet exits, neither it nor the slide can accelerate to a higher velocity. They can only decelerate.

So, assuming no outside force acting on the slide from hammer mass, mainspring, and recoil spring...the slide will lose a little velocity from rail friction and impact the frame at maybe 21 fps. Add the mentioned outside forces, assuming a 16-pound recoil spring and 23 pound mainspring...and the impact velocity is around 16-18 fps. Not exactly rock-crushing forces at work here.

A local IDPA/USPSA shooter who lives and breathes his games uses a 12-pound recoil spring with Major Power Factor ammunition. He runs through tens of thousands of rounds annually, and he only changes springs when he starts to notice sluggish return to battery. He told me that his current spring was getting a little tired after 50,000 rounds, and he intended to change it out soon. Other than the absence of bluing, his slide and frame abutments look fine.

This mirrors my own experience with my pair of range beaters that are collectively approaching 400,000 rounds. All my ammo is hardball equivalent...230/830 and 200/890...and neither pistol has been run with a spring heavier than 16 pounds, and for 90% of that use...I used 14 pound springs that I changed about every 5,000 rounds.

Neither pistol ever saw a shock buff until recently when a friend gave me a pair to try. I tossed'em in the parts drawer after about 250 rounds each in case anybody wants'em.

No abutment damage noted.

Thompsoncustom

December 5, 2012, 06:01 PM

Can't really add much to that but here is some real full house 10mm ammo.

http://www.underwoodammo.com/10mmauto.aspx

JROC

December 5, 2012, 06:19 PM

^ Yes Underwood Ammo makes some great 10mm loads. I shot some back to back with some similarly rated DT ammo,(both where 200 gr JHP's rated at 1200 FPS I believe) and you could honestly tell that the Underwood Ammo noticeably hotter.

I own a G20, and run a 22lb recoil spring in it. I believe the OEM recoil assemble uses either a 15lb or 17lb recoil spring. The 22lb spring works great and has never given me a single problem even with cheap, watered down target ammo.

harrygunner

December 5, 2012, 07:02 PM

Doing the calculations eliminates other "strains of arguments".

'1911Tuner' is pretty good with classical mechanics. A while back, I did similar calculations on the sensitivity of slide speed to recoil spring rates.

My conclusion is, recoil springs are not intended to arrest the movement of the slide.

Compared to a .45 ACP, a 10mm 180gr at 1300 ft/s or a 200gr at 1200 ft/s adds 3-4 ft/s to the slide speeds 'tuner posted. To arrest that additional slide speed, recoil springs would have to have more than twice the rating. Such springs would be so strong, most humans could not rack the slide.

To understand this, note slide speed reduction goes as the square root of the recoil spring rate ratio. So, going from 16 to 18lb or 20 to 22lb has far less effect than what most must imagine.

BrainOnSigs

December 5, 2012, 08:17 PM

It seems to have just enough effect.

I run a 22# spring with my G20SF. I shoot Underwood ammo almost exclusively. (Great ammo....it has always chrono'd over the advertised FPS). The biggest reason I run the heavier spring is because the G20's factory recoil spring allows the breech face to open too soon. The spreads were in excess of 100 fps before installing the 22# spring. After installing the spring the spreads were reduced to a very reasonable 25-30 FPS.

Another factor is the springs themselves. I have run a 22# non-captive Wolff spring set-up and a 22# Glock captive spring set-up.The Wolff non-captive set-up is noticeably stiffer than the captive spring even though both are rated at 22#.

Dakotared

December 5, 2012, 09:04 PM

I run a 20lb spring in my EAA witness. I have the full size wonder finish one and the only bullets I found that it does not like is simiwad cutters. It is a great gun and fits my hand way better then the glock 20 and as a nice side the witness comes with a barrel that you can shoot 10mm with unlike the glock that you need a after market one so you don't blow it up!!;)

Buck13

December 6, 2012, 12:11 PM

Can't really add much to that but here is some real full house 10mm ammo.

http://www.underwoodammo.com/10mmauto.aspx
Neat! I wonder what powder they are using in the 220 gr. lead round? That's some hot stuff.

Buck13

December 6, 2012, 12:18 PM

To understand this, note slide speed reduction goes as the square root of the recoil spring rate ratio. So, going from 16 to 18lb or 20 to 22lb has far less effect than what most must imagine.

OK, if (or let's be hopeful and say "when":)) I get a Witness, I'll be less tempted to mess with the springs and more concerned with the fodder, if I have any problems with cycling.

The tough part is choosing which model. The basic metal frame I shot was pretty nice! I'd kinda prefer a DA trigger, so that may save me from paying more for the longer barreled versions.

kerreckt

December 6, 2012, 12:29 PM

I have a full size Witness 10mm with a 18lb Wolff spring and it handles ammo I hand load to the full 10mm potential with no problem. I have never had any feed problems. It is a very accurate pistol.

ku4hx

December 6, 2012, 12:29 PM

I own two 10mm (Glock Gen2 20 and a Smith 1006) both were bought in the early '90s. Combined round count for the two of them is approaching 48,000.

Being the anal retentive type, I bought replacement recoil springs that essentially bracketed the OEM spring and gave me a few lighter and heavier for each gun.

About five years ago I returned both guns to full as-purchased factory specifications. I've loaded everything from Fairy poots to Buffalo Bore/Double Tap equivalents and a few I never want to repeat. The facts are in my case, matching the round to the load worked just fine but the marginal gain/difference for spring weights other than the OEM supplied just wasn't worth the effort when you stick with published starting and max loads. Which now in my quest to simplify life post retirement is exactly my goal.